1. Field of the Invention
The present invention relates to an endoscope, and more in particular, to an endoscope that includes a treatment instrument elevation support for guiding a treatment instrument that is introduced via a treatment instrument insertion channel.
2. Description of the Invention
An endoscope roughly comprises: an insertion portion, to be inserted into a coelom; a control portion, connected to the base end of the insertion portion; and a connector, attached to the control portion by a cord. The insertion portion is constituted by connecting, in the named order from near the distal end, a head made of a hard material; a bending portion; and an introduction portion, which is the proximal end of the insertion portion. The head includes an observation portion, for observations performed inside a body; and a treatment instrument guide portion, for guiding a treatment instrument, which is inserted at the control portion, through a treatment instrument insertion channel.
In the treatment instrument guide portion, a treatment instrument is introduced through an opening that communicates with the treatment instrument insertion channel, and is guided in a predetermined direction by a treatment instrument elevation support. The treatment instrument elevation support is coupled with a wire that is connected to an elevation lever provided for the control portion, and can be rotated by using the elevation lever. The treatment instrument elevation support can be raised by using the elevation lever, and with the treatment instrument elevation support being up, in a predetermined direction, the treatment instrument can be stably guided. JP-UM-A-60-180401 is relevant to the present invention.
When the treatment instrument elevation support is elevated at a predetermined angle or greater, the distal end projects outward, beyond the outer circumference of the head. In this state, were the insertion portion to be inserted into or removed from the coelom, the projected treatment instrument elevation support would injure the surface of the coelom. Therefore, for safety, before the insertion or extraction of the insertion portion is performed, it must be confirmed that the treatment instrument elevation support is reclined.
A determination of whether the treatment instrument elevation support is reclined or is elevated, can be made by observing an image. According to the description of an endoscope disclosed in JP-UM-A-60-180401, when the treatment instrument elevation support is elevated, an image of at least part of the support can be captured in the observation view field.
With the structure described in JP-UM-A-60-180401, an image of part of the treatment instrument elevation support in the elevated state is included in the view field; however, when the treatment instrument elevation support is reclined, an image is not always captured in the view field. As is described above, the treatment instrument elevation support must be reclined when the insertion portion is inserted or removed, and there is a demand that the reclined state of the treatment instrument elevation support be properly confirmed before an insertion/removal operation is performed.